JP3628792B2 - Tire deformation detection device and vehicle driving support device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire deformation detection device that detects the degree of deformation of a tire that is used as basic data during vehicle travel control and the like, and a vehicle driving support device that uses the tire deformation detection device.
[0002]
[Prior art]
As one of vehicle driving support devices, there is known a device that calculates a predicted traveling locus based on a current traveling state of a vehicle and superimposes this on an actual road ahead to display the head up. In this device, in calculating the predicted travel path, in addition to various physical quantities indicating the travel state such as the vehicle travel speed, acceleration / deceleration, steering angle, yaw rate, etc., the road surface friction coefficient, which is the friction coefficient between the road surface and the tire. Is required. Conventionally, this road surface friction coefficient is detected by detecting the unevenness of the road surface or the wetness of the road surface during rain using an optical sensor and setting an estimated value based on this detection result (special feature). (Kaisho 63-83424). Such estimation of the road surface friction coefficient is also required for an anti-lock / brake system or the like, and is performed by detecting the difference in the rotational speeds of the left and right wheels, lateral acceleration, etc. in addition to the unevenness of the road surface.
[0003]
[Problems to be solved by the invention]
The above-described method of detecting the road surface condition and estimating the road surface friction coefficient based on the detection result has a problem that it is difficult to achieve high estimation accuracy because the degree of tire wear is not considered. In addition, since the method for estimating the road surface friction coefficient from the difference between the rotational speeds of the left and right wheels, the lateral acceleration, and the like is indirect, it is difficult to achieve high estimation accuracy.
Accordingly, an object of the present invention is to provide a novel apparatus capable of estimating a road surface friction coefficient with high accuracy.
[0004]
[Means for Solving the Problems]
A tire deformation detection device according to the present invention includes a mark formed at a predetermined portion of a tire, mark position detection means for detecting the position of the mark from another predetermined portion of the tire, and the mark position detection means. Tire deformation detecting means for detecting the deformation of the tire from the position of the mark detected by. Further, in this tire deformation detection device, non-contact type power transmission means for transmitting operating power from the former to the latter between the vehicle body and the mark position detection means, the mark position detection means and the tire A wireless transmission path for transmitting the detection result of the mark position as an electric signal is formed between the deformation detection means.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the embodiment of the present invention, the mark is formed on the inner peripheral surface of the crown portion of the tire, and the position detecting means is formed at a location facing the mark on the rim. This position detection means is a two-dimensional position detection means for detecting a change in the position of the mark in the circumference and width direction of the tire, and is composed of an optical position detection means provided with illumination means. This optical position detecting means is composed of a two-dimensional PSD element that generates an electrical signal having a magnitude corresponding to the image forming position of the mark. Furthermore, a non-contact type power transmission means for transmitting operating power is formed between the vehicle body and the mark position detection means, and between the mark position detection means and the tire deformation detection means, A wireless transmission path for transmitting the detection result of the mark position as an electrical signal is formed.
[0006]
【Example】
FIG. 1 is a cross-sectional view showing a main part of a tire deformation detection device of one embodiment of the present invention together with a tire to be detected. A small-diameter circular mark 1 is formed on the surface of the carcass K inside the crown portion C in contact with the road surface of the tire T. The mark 1 is formed, for example, by sticking a metal flake or the like having a good reflectance with respect to the light beam on the surface of the carcass K with an adhesive.
[0007]
A mark position detector 2 is installed at a predetermined location on the rim R facing the mark 1. The mark position detector 2 is built in a cylindrical case made of resin, and after the case is press-fitted into an opening provided in the rim R, an adhesive is applied to the rim R. Is held on. The mark position detector 2 is provided with an antenna 3 for transmitting the mark position detected by the mark position detector 2 to a tire deformation detection circuit installed on the vehicle body side by an FM signal.
[0008]
The tire T is fixed to the rotating shaft of the vehicle via bolts and nuts at the center of the rim R. A disk-shaped substrate 4 made of resin is fixed to the end of the rotating shaft, and coils 5 and 6 for electromagnetic coupling are formed on the front and back surfaces of the substrate. . The coils 5 and 6 are electrically connected via electric wires passing through the substrate. A coil 7 is formed at a position on the vehicle body side facing the coil 5 formed on the substrate 4, and a coil 8 is formed at a position on the rim R side facing the coil 6 formed on the substrate 4. Has been.
[0009]
AC power supplied from a power supply circuit (not shown) installed on the vehicle body side is supplied to the mark position detector 2 through the coil 7, the coil 5, the coil 6, and the coil 8 that are installed facing each other, and inside the mark position detector 2. It is converted into DC power by the installed rectification / smoothing circuit and supplied as DC power to each circuit inside the mark position detector 2.
[0010]
At the tip of the mark position detector 2 facing the mark 1, an optical head having a configuration as illustrated in the cross-sectional view of FIG. 2 is formed inside a transparent window. In this optical head, a light emitting diode (PD) fixed on a resin substrate SB and a two-dimensional position detection element (PSD) are installed in close proximity, and a light transmission lens TL is disposed in front of each. And a light receiving lens RD. The light emitted from the light emitting diode PD is irradiated to the inside of the tire through the light transmission lens TL while expanding the spot diameter, and the mark 1 is irradiated. The light beam reflected by the mark 1 travels toward the center of the tire and enters the surface of the two-dimensional PSD while being converged by the light receiving lens RL of the mark position detector 2.
[0011]
As shown in the perspective view of FIG. 3, the two-dimensional PSD has a pn junction formed at the interface between the rectangular p-type semiconductor layer and the n-type semiconductor layer, and the p-type layer on the surface side A pair of electrodes (13a, 13b) facing each other is formed in the peripheral portion along one direction (referred to as the x-axis direction), and the peripheral portion along the other direction (referred to as the y-axis direction) perpendicular thereto is formed. Opposite electrode pairs (14a, 14b) are formed, and an electrode 15 is formed at the center of the n-type layer on the back side. This two-dimensional PSD corresponds to a commercially available Si one-dimensional PSD (position detecting element) manufactured by Hamamatsu Photonics, which is expanded to a two-dimensional structure.
[0012]
In the x-axis direction, the electrode pair (13a, 13b) and the electrode 15 are connected to various circuits including operational amplifiers as shown in FIG. The electric signal output from the electrode 13a is amplified by the amplifier circuit A1, and then supplied to one input terminal of each of the addition circuit AD and the subtraction circuit SB. The electric signal output from the electrode 13b is amplified by the amplifier circuit A2, and then supplied to the other input terminal of each of the addition circuit AD and the subtraction circuit SB. The output of the adder circuit AD is supplied as an addition signal Σ1 to one input terminal of the analog division circuit U6 via the amplifier circuit A3 that gives attenuation, and the output of the subtraction circuit SB is directly used as the difference signal Δ1 as the other signal of the analog division circuit U6. Supplied to the input terminal. From the analog division circuit U6, a differential signal (Δ1 / Σ1) normalized by the addition signal is output as a position signal.
[0013]
The position signal (Δ1 / Σ1) becomes zero if the spot reflected by the mark 1 and incident on the two-dimensional PSD while being focused by the light receiving lens RL exists at the center of the two-dimensional PSD, and the spot is two-dimensional. When shifting from the center of the PSD to the left and right along the x-axis direction, a voltage having a polarity proportional to the shift amount and in accordance with the shift direction is obtained. Similarly, also in the y-axis direction, the electrode pair (14a, 15b) and the electrode 15 are connected in the same manner to various circuits including operational amplifiers configured in the same manner as in FIG. An axial position signal (Δ1 / Σ1) is output.
[0014]
The amount of deviation of the mark 1 in the width direction of the tire is detected by the two-dimensional PSD as the amount of deviation from the center in the x-axis direction, and the amount of deviation in the circumferential direction of the tire is detected from the center by the two-dimensional PSD in the y-axis direction. The mounting angle in the mark position detector 2 is adjusted so as to be detected as the amount of deviation.
[0015]
The position detection signal in the x-axis direction is supplied to the input terminal In of the frequency modulation circuit having the configuration shown in FIG. When the capacitance of the variable capacitance diode VC changes according to the DC voltage supplied to the input terminal In, the oscillation frequency of the frequency modulation circuit changes. From the output terminal Out, according to the position detection signal in the x-axis direction. A signal with a changing frequency is output. Similarly, the position detection signal in the y-axis direction is also converted into a signal having a frequency that changes in accordance with the position detection signal in the y-axis direction by the y-axis frequency modulation circuit having the same configuration as that in FIG.
[0016]
The FM signal modulated by the position detection signal in the x-axis direction and the position detection signal in the Y-axis direction is supplied to the antenna 3 in FIG. 1 and radiated into the air. The FM signal radiated into the air is supplied to a tire deformation detector installed on the vehicle body side via an antenna (not shown) installed on the vehicle body side. This tire deformation detector includes an FM signal demodulating circuit, an A / D converter, and a digital processor. By detecting the FM signal received from the mark position detector 2, position detection in the x and y axis directions is performed. The signal is restored, converted into a digital signal, and processed by a digital processor to detect the degree of deformation in the width direction and the circumferential direction in consideration of dimensions such as the tire diameter.
[0017]
Preferably, the signal transmitted from the mark position detector 2 includes an identification code indicating the type of tire in addition to the position detection result. In the tire deformation detector on the main body side that has received this signal, By identifying the identification code, the tire type and diameter are identified.
[0018]
The tire deformation signal detected by the digital processor in the tire deformation detector is sent to a higher-level device such as a vehicle predicted travel locus calculation device or an anti-lock / brake device. Alternatively, it is possible to adopt a configuration in which a tire deformation detection unit having the above-described functions is formed as a part in a higher-level device such as an existing predicted travel locus calculation device or antilock / brake device.
[0019]
FIG. 6 is a conceptual diagram showing an example of characteristics used to estimate the relationship between the amount of tire deformation in the width direction and the steering force, which is processed by a higher-level device such as a vehicle predicted travel locus calculation device or an anti-lock / brake device. FIG. In a range where the steering force is small, the amount of deformation of the tire in the width direction increases substantially in proportion to the steering force. In this case, the proportional constant is estimated to be approximately proportional to the road surface friction coefficient. Similarly, the road surface friction coefficient can be estimated from the relationship between the acceleration or deceleration and the amount of deformation of the tire in the circumferential direction.
[0020]
As described above, the configuration in which the position of the mark is detected using the two-dimensional PSD by taking advantage of the low cost has been exemplified. However, in the case where a slight increase in cost can be allowed, other appropriate optical devices such as a CCD camera. It is also possible to employ a configuration in which the position of the mark is detected using. In addition, the detection of the mark position is not limited to an optical method, but an electromagnetic position detection method using a change in capacitance, a change in magnetic characteristics, or the like, or a predetermined point of interest in a tire and a reference Other appropriate methods, such as a method of detecting the tension of the wire stretched between the predetermined portions, can also be applied.
[0021]
Moreover, the structure which inserts the front-end | tip part in the inside of a tire by press-fitting and fixing the mark position detector to the rim | limb was illustrated. However, it is also possible to provide a configuration in which a strong optical window is provided on the rim and a mark position detector is installed on the rim outside the tire and the mark position is detected through the optical window.
[0022]
Furthermore, although the configuration in which operating power is supplied to the mark position detector from the vehicle body side is illustrated, the mark position detector can be configured to operate with a built-in battery without supplying such power. . Moreover, although the configuration in which the detection result is transmitted by the FM signal from the mark position detector to the tire deformation detector on the main body side is exemplified, other modulation methods such as an AM signal may be applied. Furthermore, the configuration for transmitting the detection result of the mark position via the wireless transmission path is illustrated, but the detection result of the mark position is transmitted to the main body side via an electromagnetic coupling mechanism such as a coil in the same manner as the operating power supply method. It is also possible to adopt a configuration that transmits to
[0023]
Further, it is possible to add a function of measuring information on the air pressure in the tire that may be necessary for analysis of tire deformation with a mark position detector and transmitting the measurement result to the vehicle main body side device. As described above, in addition to the detection result of the mark position in the two-dimensional direction, when adopting a configuration in which various data such as a tire identification code and air pressure are sent from the mark position detector to the vehicle main body side, The digital signal including various information can be transmitted to the main body side using a modulation method such as phase shift keying (PSK).
[0024]
【The invention's effect】
As described above in detail, the tire deformation detection device according to the present invention detects the deformation of the tire by detecting the position of the mark formed at the predetermined position of the tire from the other predetermined position of the tire. Because it is a configuration to detect, it is possible to calculate the amount of road surface friction coefficient required for various types of control and the calculation of the predicted driving locus performed by various vehicle driving support systems such as a vehicle's predicted driving locus calculation device and anti-lock / brake system. There is an advantage that it can be estimated with high accuracy.
[0025]
Further, by using an inexpensive two-dimensional PSD as a two-dimensional position detection sensor attached to a tire, the cost of the apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a tire deformation detection device according to an embodiment of the present invention together with a tire to be detected.
2 is a cross-sectional view illustrating the configuration of an optical head of the mark position detector 2 in FIG. 1;
3 is a perspective view for explaining an example of the configuration of a two-dimensional PSD installed in the optical head of FIG. 2; FIG.
4 is a circuit diagram showing a configuration of a circuit that outputs a position signal by connecting an electrode pair (13a, 13b) in the x-axis direction of the two-dimensional PSD of FIG. 3 and an electrode 15 to an operational amplifier.
FIG. 5 is a circuit diagram showing an example of a configuration of an FM signal generation circuit that generates an FM signal modulated by a position detection signal.
FIG. 6 is a characteristic diagram for explaining an example in which a road surface friction coefficient is estimated from a relationship between a steering force and a tire deformation amount in the width direction.
[Explanation of symbols]
T Tire R Rim C Crown K Carcass 1 Mark 2 Mark position detector 3 Antenna 4 Substrate 5, 6, 7, 8 Coil 11 for transmitting AC power for operation from the vehicle body side to the mark position detector 2 p-type semiconductor layer 12 n-type semiconductor layer

Claims (9)

A mark formed at a predetermined location of the tire, mark position detection means for detecting the position of the mark from another predetermined location of the tire, and deformation of the tire from the position of the mark detected by the mark position detection means and further comprising a tire deformation detecting means for detecting,
A tire deformation detection device , wherein non-contact type power transmission means for transmitting operating power from the former to the latter is formed between a vehicle body and the mark position detection means. . A mark formed at a predetermined location of the tire, mark position detection means for detecting the position of the mark from another predetermined location of the tire, and deformation of the tire from the position of the mark detected by the mark position detection means and further comprising a tire deformation detecting means for detecting,
A tire deformation detection device, wherein a wireless transmission path for transmitting a mark position detection result as an electric signal is formed between the mark position detection means and the tire deformation detection means . In either claim 1 or 2 ,
The tire deformation detecting device, wherein the mark is formed on an inner peripheral surface of a crown portion of the tire, and the position detecting means is formed at a location on the rim facing the mark. In claim 3 ,
The tire deformation detection device, wherein the position detection means is a two-dimensional position detection means for detecting a change in a position of the mark in a circumferential direction and a width direction of the tire. In any one of Claims 1 thru | or 4 ,
The tire deformation detection device, wherein the position detection means is an optical position detection device provided with illumination means. In claim 5 ,
The apparatus for detecting tire deformation, wherein the optical position detecting means includes a two-dimensional PSD element that generates an electric signal having a magnitude corresponding to an image forming position of the mark. A mark formed at a predetermined position of the tire, a mark position detecting means for detecting the position of the mark from another predetermined position of the tire, and a deformation of the tire from the position of the mark detected by the mark position detecting means A tire deformation detection unit including tire deformation detection means for performing,
A vehicle driving support device comprising: a road surface friction coefficient estimating unit that estimates a road surface friction coefficient from a relationship between a tire deformation amount detected by the tire deformation detecting unit and a physical amount related to a running state of the vehicle. . In claim 7 ,
The mark position detection means detects the position in the width direction of the tire of the mark formed on the inner peripheral surface of the crown portion of the tire,
The road surface friction coefficient estimating unit estimates a road surface friction coefficient from a relationship between a deformation amount in the width direction of the tire detected by the mark position detection unit and a steering force, and a vehicle driving support device according to claim 1. In claim 7 ,
The mark position detection means detects the position of the mark in the circumferential direction of the tire formed on the inner peripheral surface of the crown portion of the tire,
The road surface friction coefficient estimating unit estimates a road surface friction coefficient from the relationship between the amount of deformation in the circumferential direction of the tire detected by the mark position detecting means and the acceleration / deceleration, and the vehicle driving support device according to claim 1.

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